This section provides background information related to the present disclosure which is not necessarily prior art. This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features.
Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the United States. For end-stage COPD, lung transplantation is the only curative therapy available at this time. The demand for lungs, however, exceeds the donor supply, resulting in long wait-times and ineligibility. An oxygenator that is driven entirely by the heart and designed to provide pulmonary support, primarily by clearance of carbon dioxide, is a promising alternative for end-stage COPD patients waiting for or ineligible for lung transplantation. The effectiveness and life span of such an oxygenator can be greatly increased by generating secondary flows, which enhance the mixing of blood, thereby reducing thrombogenecity and improving efficiency of gas transport. The efficiency of an oxygenator can be further increased by having a relatively short gas path, which will reduce the buildup of carbon dioxide in the ventilating gas and thereby increase the gradient for carbon dioxide clearance.
In view of the foregoing, it is the objective of the present teachings to provide a pumpless concentric artificial oxygenator, driven by external perfusion, having a compact size, low priming volume, and the ability to adequately remove carbon dioxide from and oxygenate blood using a short gas path and a plurality of single-gated baffles with specific placements that passively generate orderly secondary flows and recirculation, enhancing the mixing of blood and thereby reducing thrombogenecity and improving efficiency of gas exchange.
This concentric artificial oxygenator technology of the present teachings (also synonymously called an artificial lung, prosthetic lung, oxygenator, membrane oxygenator, and the like—these terms may be used interchangeably herein) can be used to oxygenate blood and remove carbon dioxide (CO2) in heart-lung machines including extracorporeal devices (ECMO). In this application, the artificial lung can be used for patients requiring heart operations and support for acute heart and/or lung failure. A heart-lung machine is used for one million patients per year in the United States. Thus, this technology can help a significant patient population.
This technology uses gated spiral flow of the blood which results in secondary flow to increase oxygenation. The secondary flow results in increased mixing which improves oxygenation. The formation of blood clots (thrombus) is a major problem that limits the use of heart-lung machines and extracorporeal membrane oxygenation (ECMO) to a few hours and a few weeks, respectively. This technology reduces the tendency to form blood clots and extends the time that patients can be managed using a prosthetic lung. This technology may also act as a bridge to transplant for lung transplant candidates whom are adversely affected by the limited supply of donor lungs. This technology can significantly improve surgical and intensive care outcomes.
In summary, the present teachings provide an artificial lung having a plurality of baffles in the blood phase to create mixing and improve gas exchange efficiency. The lung is designed for use as an implantable or wearable device driven by the patient's native circulation and can also be used with a pump in a heart-lung machine.
In some embodiments, the artificial lung of the present teachings is a hollow fiber membrane lung with concentric baffles in the blood flow path designed to increase mixing and thereby increase the efficiency of gas exchange, and to minimize stagnation thereby minimizing clotting in the artificial lung of the present teachings. The artificial lung of the present teachings has low blood flow resistance permitting perfusion via the pulmonary artery or via a peripheral artery, such as the subclavian artery. This resistance is achieved by the placement and size of the gates in the baffles and by modifying the density of the fiber bundle. In some embodiments, the resistance ranges from 10 to 30 mmHg per liter of blood flow, depending on the size and intended application of the artificial lung of the present teachings.
In some embodiments, the artificial lung of the present teachings achieves minimal or no thrombogenicity in light of its unique design and configuration. For example, in some embodiments, the artificial lung is capable of minimizing clotting and platelet activation due to its increased gas transfer efficiency per membrane surface area that leads to short transit times. The artificial lung minimizes or eliminates stagnation of blood due to the design of the baffles and the position and the size of the gates. This design results in no increased shear stress that may cause platelet activation. Moreover, the hard surface components of the artificial lung of can be coated with nonthrombogenic material to further aid in minimal thrombogenicity.
In some embodiments, the artificial lung of the present teachings comprises a housing having a circular outer wall being enclosed by a first surface and a second surface to define an interior volume, a blood inlet port to permit inlet flow of blood to the housing, a blood outlet port to permit outlet flow of the blood from the housing, a gas inlet port to permit inlet flow of a gas to the housing, a gas outlet port to permit outlet flow of the gas from the housing, and a plurality of baffles concentrically disposed within the housing. The baffles are positioned to define a flow path between the blood inlet port and the blood outlet port. Each of the baffles includes one or more gate openings to permit flow of the blood along the flow path. A fiber bundle is disposed between the baffles within the flow create mixing and improve gas exchange efficiency.
In some embodiments, the size, shape, and resistance of the artificial lung of the present teachings are designed for implantable or wearable placement and application (although the artificial lung of the present teachings can be perfused with a pump, if desired).
Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.
Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings.